18th Century Russian Icon

I bought this as a genuine Russian Icon, believed to be from the 18th Century. It is of paper mounted onto an old piece of wood and measures 5 7/16" x 4 1/4".
It certainly looks to be genuinely very old, and I believe it to be a genuine Icon at least 100 years of age but whether it is 18th Century or not I simply can not verify. The condition is as portrayed in the pictures and without doubt it is a very interesting and intriguing piece that was purchased in Russia around 1980.